[clang] clang/limits.h: Avoid including limits.h twice (PR #120526)

[YunQiang Su via cfe-commits]

wzssyqa wrote:

> but that leads to the question of: why is including musl's limits.h a problem?

It cause some warning like
```
./include/bits/xopen_lim.h:84:10: warning: "NL_NMAX" redefined
   84 | # define NL_NMAX        INT_MAX
```

https://github.com/llvm/llvm-project/pull/120526